F. Gimeno-Nogues

Signals for a transition from surface to bulk emission in thermal multifragmentation.

Excitation-energy-gated two-fragment correlation functions have been studied between E(*)/A = (2-9)A MeV for equilibriumlike sources formed in 8-10 GeV/c pi(-) and p+197Au reactions. Comparison with an N-body Coulomb-trajectory code shows an order of magnitude decrease in the fragment emission time in the interval E(*)/A = (2-5)A MeV, followed by a nearly constant breakup time at higher excitation energy. The decrease in emission time is strongly correlated with the onset of multifragmentation and thermally induced radial expansion, consistent with a transition from surface-dominated to bulk emission expected for spinodal decomposition.

Isospin equilibration in the reaction EA = 33, 45 MeV 40Ar, 40Ca + 58Fe, 58Ni☆

Abstract Isobaric beams from the K500 superconducting cyclotron have been used to study the effects the N Z of the target and projectile on the isobaric composition of emitted fragments for the reactions of E A = 33, 45 MeV 40 Ca, 40 Ar + 58 Fe, 58 Ni. At E A = 33 MeV , the system behaves as if it is equilibrated prior to the emission of reaction products, while at E A = 45 MeV the same composite system results in different isobaric ratios depending on the initial projectile and target; therefore, the emission of reaction products occurs prior to complete equilibration.

Thermal excitation of heavy nuclei with 5–15 GeV/c antiproton, proton and pion beams

Abstract Excitation-energy distributions have been derived from measurements of 5.0–14.6 GeV/c antiproton, proton and pion reactions with 197 Au target nuclei, using the ISiS 4 π detector array. The maximum probability for producing high excitation-energy events is found for the 8 GeV/c antiproton beam relative to other hadrons, 3 He and p beams from LEAR. For protons and pions, the excitation-energy distributions are nearly independent of hadron type and beam momentum above about 8 GeV/c. The excitation energy enhancement for p beams and the saturation effect are qualitatively consistent with intranuclear cascade code predictions. For all systems studied, maximum cluster sizes are observed for residues with E ∗ /A∼6 MeV.

FAUST : A NEW FORWARD ARRAY DETECTOR

A new forward array has been designed and constructed using silicon technology. The detectors telescopes are Si followed by CsI that are read out by photodiodes. This combination allows for isotopic resolution through Z = 6. The special edge-mounting of the silicon detector combined with the ring-like structure of the overall array has allowed for a design that minimizes dead area.

MULTIFRAGMENTATION : THERMAL VS. DYNAMIC EFFECTS

Reactions of 1.8 – 4.8 GeV 3He, 5.0 – 9.2 GeV/c π− and 6.0 – 14.6 GeV/c protons with natAg and 197Au targets have been studied with the ISiS 4π detector array. From reconstructed events, excitation-energy distributions have been determined and combined with a 2,3H3,4He isotope-ratio thermometer to study the heating curve for the thermal-like component of these reactions. Dynamic effects also manifest themselves in the data, as evidenced by deposition-energy saturation above ∼5 GeV, IMF emission during expansion, and sideways peaking of the IMF angular distributions for beam energies Eb ≥ 10 GeV.

Effects of in-medium cross sections and optical potential on thermal-source formation in p+{sup 197}Au reactions at 6.2-14.6 GeV/c

Effects of in-medium cross sections and of optical potential on preequilibrium emission and on formation of a thermal source are investigated by comparing the results of transport simulations with experimental results from the

Probing the nuclear EOS with GeV light-ion beams

p+^{197}\mathrm{Au}

Multifragmentation with GeV light-ion beams

reaction at

Dynamic and Statistical Effects in Light-Ion-Induced Multifragmentation

6.2\char21{}14.6\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}∕c

Hadron-Induced Multifragmentation

. The employed transport model includes light-composite-particle production and allows for inclusion of in-medium particle-particle cross-section reduction and of momentum dependence in the particle optical potentials. Compared to the past, the model incorporates improved parametrizations of elementary high-energy processes. The simulations indicate that the majority of energy deposition occurs during the first